1. Field of the Invention
The present invention relates to an image forming apparatus such as a copy machine, a printer, and a facsimile apparatus using an electrophotographic method, an electrostatic recording method, or the like.
2. Description of the Related Art
Conventionally, as an image forming apparatus using the electrophotographic method or the like, there has been a tandem-type image forming apparatus including a plurality of image forming units disposed along a rotational path of an intermediate transfer member to form a full color image.
Then, for the image forming apparatus using the intermediate transfer member, there is a technique for correcting a density by forming an adjustment toner image (hereinafter also referred to as a “patch”) at a predetermined density on the intermediate transfer member, detecting the density of the patch, and then providing a feedback according to the detected density of the patch to reflect it in an image forming condition.
Further, for the image forming apparatus using the intermediate transfer member, there is a method for cleaning the intermediate transfer member by electrostatically attracting toner to a cleaning member to remove the toner from the intermediate transfer member, which is called an electrostatic cleaning method.
However, generally, a cleaning device based on the electrostatic cleaning method is configured to remove a small amount of toner (transfer residual toner or remaining toner) remaining on the intermediate transfer member after a secondary transfer of a toner image from the intermediate transfer member onto a transfer medium. Therefore, in some cases, it may be difficult to completely remove the patch generated using a large amount of toner compared to the transfer residual toner by performing the cleaning only once.
To solve this problem, Japanese Patent Application Laid-Open No. 2006-267682 discusses a technique for detecting residual toner left without being cleaned on an intermediate transfer member, and optimizing a voltage to be applied to a cleaning member or inserting a forcible cleaning mode to forcibly clean the intermediate transfer member until the residual toner is eliminated.
However, according to the technique for detecting the residual toner on the intermediate transfer member and forcibly cleaning the intermediate transfer member until the residual toner is eliminated, the residual toner should be detected after the residual toner on the intermediate transfer member passes through a cleaning portion. Therefore, the productivity is reduced according to a time taken until the residual toner passes through the cleaning portion. Further, a cleaning setting is changed after the residual toner is detected, whereby a cleaning failure occurs in an image (a printed matter) formed during this period.